Apparatus for interfacing a wireless local network and a wired voice telecommunications system

ABSTRACT

An apparatus for interfacing a wireless local area network with a wide area, cellular or public switched telephone network including the function of a wireless LAN base station or access point, and a gateway. The interface may contain one or more different types of gateways, including a PSTN voice gateway, an analog modem gateway, and others. The apparatus may also include a well designed to receive the handset or mobile computer device to recharge the battery as well as to automatically transfer data when the phone or device is secured in the well.

RELATED APPLICATION

This is a continuation of U.S. application Ser. No. 10/454,736, filed onJun. 4, 2003, now abandoned which is a divisional application of U.S.application Ser. No. 09/213,958, filed Dec. 17, 1998, now U.S. Pat. No.6,600,734.

This application is related to U.S. patent application Ser. No.08/794,782, filed Feb. 3, 1997.

This application is also related to U.S. patent application Ser. No.08/906,722, filed Aug. 5, 1997.

This application is also related to U.S. patent application Ser. No.09/008,710, filed Jan. 16, 1998.

This application is also related to U.S. patent application Ser. No.09/047,015, filed Mar. 24, 1998.

Each of the above applications are expressly incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of voice communications overdifferent types of communications networks. More specifically, thepresent invention relates to an apparatus which interfaces a wireless IPnetwork and a wide area network or public switched telephone network(PSTN) for voice communications.

2. The Background Art

Public switched telephone networks have been used for many years forvoice communication. The typical telephone converts sound waves intoanalog signals, which are then transmitted through the public switchedtelephone network to another telephone, which converts the analog audiosignals back into sound waves. In recent years, wireless and cellulartelephones have been rising in popularity, due to their mobility. Usersare no longer tied to a stationary telephone, but are free to carrytheir telephones with them.

With the advent of computers and fax machines, there arose a need totransmit data in a similar fashion. Due to the fact that analogtelephone lines were already in existence in every part of the nation,these lines were also used in the transmission of data. Specificprotocols were designed, such as the V.32 protocol, which specified howdigital data is encoded into analog signals for transmission over publicswitched telephone networks.

The apparatus that performs conversion from digital data to an analogtelephone signal is known as an analog modem. Analog modems do notrequire dedicated or specialized lines, as they use pre-existingtelephone lines, which are already in existence in nearly every home inthe country. The main drawback, however, is in the relatively low speedof transmissions. Current protocols allow only up to about 56 Kbps to betransmitted through an analog phone line, and FCC regulations currentlylimit this number to 53 Kbps due to power output concerns.

Users who require faster transmission speeds have turned to carrierswhich allow digital transmission, which not only provide much fasterspeeds and higher bandwidth, but also reduce errors that occur duringtransmission. Examples of such carriers are ISDN lines, T1 and T3 lines,and cable lines. ISDN lines are in actuality twisted pair telephonelines. While ISDN service allows a user to obtain digital transmissionwithout a dedicated or specialized line, the inherent physical drawbacksof twisted pair lines limits the amount of bandwidth and speed of suchsystems. T1 and T3 lines are specialized, dedicated lines (T1 lines cancarry up to 1.544 Mbps while T3 lines can carry up to 44.736 Mbps.

Cable modems interface to coaxial cable lines that are typically usedfor providing cable television signals into homes and they provide alarge amount of bandwidth. While it is generally necessary for the cableprovider to upgrade the overall cable network system in order to enableInternet access through cable modems, it is generally not necessary toinstall new lines into homes.

Wide Area Networks (WANS) using wireless data communications techniquesand systems have been generally available for many years.Implementations exist which employ microwave radio-frequency (RF)communication systems and frequency-modulated (FM) radio communications.The data rate is generally up to 19.2 Kbps, which is sufficient for theintended class of applications. Frequency-modulated communicationtechniques include both conventional point-to-point radio and broadcast.These systems include RAM Mobile Data Service using the Mobitexprotocol; the Advanced Radio Data Information Service (ARDIS),manufactured by ARDIS Company, Lincolnshire, Ill.; and the CellularDigital Packet Data (CDPD) service.

The ARDIS system, for example, uses a dedicated radio network whichincludes a number of radio base stations deployed throughout largermetropolitan areas in the United States. The remote devices in the fieldcommunicated with the base stations, and vice versa. The base stationsare fixed and can cover an approximate radius of 15 to 20 miles whentransmitting and receiving. The base stations communicate with a limitednumber of radio network controllers located at various points throughoutthe United States. Each radio network controller is responsible formaintaining authorization and registration of the remote terminals. Theradio network controllers are further connected to one of three networkhubs. The network hubs are connected by dedicated leased lines and areaccessed by the customer host applications to send and receive data toand from the remote devices. The customer host applications are alsoconnected to the network hubs by dedicated leased line or through avalue added network (VAN).

Wireless local area networks (LANs) are used in business applicationssuch as inventory, price verification mark-down, portable point of sale,order entry, shipping, receiving and package tracking. Wireless localarea networks use infrared or radio frequency communications channels tocommunicate between portable or mobile computer units and stationaryaccess points or base stations. These access points are in turnconnected by a wired or wireless communication channel to a networkinfrastructure which connects groups of access points together to form alocal area network, including, optionally, one or more host computersystems.

Wireless infrared and radio frequency (RF) protocols are known whichsupport the logical interconnection of portable roaming terminals havinga variety of types of communication capabilities to host computers. Thelogical interconnections are based upon an infrastructure in which atleast some each of the remote terminals are capable of communicatingwith at least two of the access points when located within apredetermined range therefrom, each terminal unit being normallyassociated with and in communication with a single one of such accesspoints. Based on the overall spatial layout, response time, and loadingrequirements of the network, different networking schemes andcommunication protocols have been designed so as to most efficientlyregulate the association of the mobile unit with specific access points,and the availability of the communication channel to individual mobileunits for broadcasting.

One such protocol is described in U.S. Pat. Nos. 5,029,183; 5,142,550;5,280,498; and 5,668,803 each assigned to Symbol Technologies, Inc. andincorporated herein by reference.

Another such protocol is described in U.S. Pat. No. 5,673,031. Stillanother protocol is set forth in the IEEE Standard 802.11 entitled“Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY)Specifications” available from the IEEE Standards Department,Piscataway, N.J. (hereinafter the “IEEE 802.11 Standard”).

The IEEE 802.11 Standard permits either infrared or RF communications,at 1 Mbps and 2 Mbps data rates, a medium access technique similar tocarrier sense multiple access/collision avoidance (CSMA/CA), apower-save mode particularly important for battery-operated mobileunits, seamless roaming in a full cellular network, high throughputoperation, diverse antennae systems designed to eliminate “dead spots”,and an easy interface to existing network infrastructures.

The basic specifications for the communications of audio, video andmultimedia that are applicable to the networks pertaining to the presentinvention are set forth in the International Telecommunications UnionTelecommunication Standards Sect (ITU-T) standards H.320-323.

The H.321 recommendation relates to asynchronous transfer mode (ATM)channels, H.322 to guaranteed Quality of Service LANs, and H.323 topacket based systems. Data packets are created from a compressed datastream of digital voice samples. The data packets are formatted fortransmission over a data network. Since network latency and packettransmission delays can be disastrous to the intelligibility and qualityof real-time phone conversations, a variety of approaches of givingpriority of voice packets (or other real-time multimedia packets) overdata packets in the network have been proposed, thus allowingdelay-sensitive packets to supercede data packets across any networknode in any traffic situation. The H.323 recommendation also providesfor call establishment and control, including determining the sequencingand timing of establishing and disconnect procedures, as well as thecontrol of the H.323 session after it is established.

To the extent the Internet Protocol or “IP” (as set forth in IETF RFC791) is used as the network layer protocol, the recommendations of theInternational Multimedia Teleconferencing Consortium's Voice over IPForum are also applicable to such a Voice over IP (“VoIP”) network. In aVoIP network, the voice signal is digitized, encapsulated into IPpackets, and then routed between VoIP capable devices in an IP network.These packets of voice may then be delivered in real time as voicecommunications, or stored as voice mail.

Communications between a LAN and a wide area network or public switchedtelephone network are generally performed by communications controllerknown as a gateway. In the H.323 standard, a gateway generally refers toan endpoint which provides for real-time, two-way communications betweenH.323 terminals on an IP network and other ITU terminals, telephones ona PSTN, and terminals on other networks. An example of a gateway is theCisco 3600 series of Cisco Systems, Inc. The Cisco 3600 series is amodular gateway that can be configured to provide gateway functions overa wide variety of communications mediums. These include, among others,analog modem access, ISDN access, digital modem access, and voice andfax access. Other types of interfaces between wired LANs and connectedor switched networks such as frame relay and ATM networks are known. Forexample, the ATM Forum has developed a bridging implementation agreementcalled LAN Emulation (LANE). LANE relies on a LAN Emulation Server(LES), which performs MAC-to-ATM address resolution; a Broadcast andUnknown Server (BUS), which performs data broadcast; and an optional LANEmulation Configuration Server (LECS), which performs initialization andconfiguration.

Prior to the present invention, there has not been a simple anduser-transparent way to interface a wireless LAN with the diverse rangeof currently available public and private networks, including the publicswitched telephone network (PTSN), cable networks, wide area networks(WAN), cellular telephone networks, and satellite communicationsnetworks.

REFERENCES

-   ITU-T Recommendation G.711 (1993) “Pulse Code Modulation (PCM) OF    Voice Frequencies”-   ITU-T Recommendation G.729 (1995) “Coding of Speech At 8 kbit/s    Using Conjugate-Structure Algebraic-Code-Excited Linear-Prediction    (CS-ACELP)”-   ITU-T Recommendation H.323 (May, 1996): Visual Telephone Systems and    Equipment for Local Area Networks Which Provide a Non-Guaranteed    Quality of Service.-   ITU-T Recommendation Q.931 (1993): “Digital Subscriber Signaling    System No. 1 (DSS 1)—ISDN User-Network Interface Layer 3    Specification for Basic Call Control-   IETF RFC 791 “Internet Protocol”. J. Postel. Sep. 1, 1981-   IETF RFC 793 “Transmission Control Protocol”, J. Postel. Sep. 1,    1981

BRIEF DESCRIPTION OF THE INVENTION 1. Objects of the Invention

It is an object of the invention to provide an interface between awireless LAN and a gateway to a voice communications network.

It is another object of the present invention to provide an apparatusincluding a base station or access point in a wireless LAN and acommunications gateway to one or more different communications channelsor networks.

It is still another object of the invention to provide a portablewireless desk telephone which communicates with one or more stationarybase stations using a packet communications protocol, wherein the basestation interfaces to a gateway for connection to an IP network, a WAN,or the PSTN.

It is a further object of the present invention to provide an apparatuswhich functions as a data downloading station for a portable computer,pen-like bar code reader, or the like, and also transmits the downloadeddata to an IP network, a WAN or the PSTN.

It is yet another object of the invention to provide initialization andauthorization of a communications handset in a wireless LAN.

It is yet a further object of the present invention to provide anend-to-end real time voice channel through wired and wireless, andconnected and connectionless (packet switched) communications channels.

It is an even further object of the invention to provide a method whichcan be used to accomplish one or more of the above objectives.

Additional objects, advantages and novel features of the presentinvention will become apparent to those skilled in the art from thisdisclosure, including the following detail description, as well as bypractice of the invention. While the invention is described below withreference to preferred embodiments, it should be understood that theinvention is not limited thereto. Those of ordinary skill in the arthaving access to the teachings herein will recognize additionalapplications, modifications and embodiments in other fields, which arewithin the scope of the invention as disclosed and claimed herein andwith respect to which the invention could be of significant utility.

2. Features of the Invention

The present invention provides data communications network including aplurality of stationary access points and a plurality of remote mobileunits, the mobile units being capable of wirelessly communicating withat least two of the access points when located within a predeterminedrange therefrom and being normally associated with and in communicationswith a single one of such access points. A processor is located at oneof the access points for detecting a message sent by a first mobile unitand determining from the message whether it is to be routed to anothermobile unit or over another channel to another type of communicationstation; and a gateway is connected to the access point and functions toprovide a two-way voice channel of communications between the firstmobile unit and another communication station.

The present invention further provides an integral apparatus combiningthe functions of an access point and a gateway for interfacing awireless local area network with a wide area network or the publicswitched telephone network. The apparatus may contain one or moregateways, including a PSTN voice gateway (including xDSL or ISDNinterfaces), an analog modem gateway, and others such as a cable modemfor connection to a cable network. The apparatus may also include anEthernet port or serial port for connection to a wired local areanetwork. The apparatus may also include a docking station or welldesigned to receive the handset or other portable computer device torecharge the battery of the handset or optionally transfer data orcontrol information when the phone or device is secured in the well.

The present invention provides an end-to-end method for handling anoutgoing call from a caller using a handset in a wireless local areanetwork, through other communications networks to the called party,including the steps of

detecting when the user activates the mobile handset to make an outgoingcall;

receiving in the mobile handset the identification of the destination ofthe outgoing call from the user;

transmitting a ring signal to a network station corresponding to saiddestination, said ring signal designed to alert the recipient that acall is attempting to connect; and

transmitting an acknowledgment signal to the mobile handset, saidacknowledgement signal designed to alert the user that the cell made bythe user is attempting to connect. The present invention furtherincludes the steps of receiving in the handset an indication from theuser of the type of call the user desires to make, and determining inthe handset whether the user is making a network address call, anintercom call, or a name call.

The present invention further provides a method of operating a datacommunications network including a plurality of sets of stationaryaccess points and a gateway connected to the access points, and aplurality of remote mobile units, the mobile units being capable ofwirelessly communicating with at least two of the access points whenlocated within a predetermined range therefrom. Each mobile unit isnormally associated with and in communications with a single one of suchaccess points, and has a single network address that is selectable froma set of network addresses that is utilized by the mobile unit onlywhile such mobile unit is active.

The method includes the steps of storing a set of network addressesavailable for use by users in a server computer on the network;transmitting a network address request to the server computer from afirst mobile unit; and assigning a network address from the set ofnetwork addresses available to said first mobile unit. The methodfurther includes providing identification information of the user fromsaid first mobile unit to an authentication server; validating the userprivileges by the authentication server and communicating suchvalidation to said first mobile unit; and transmitting the networkaddress associated with the user's mobile unit to the telephony gateway.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a diagram illustrating a wireless local area network in whichthe present invention may be implemented.

FIG. 2 is a timing diagram showing RF transmission versus time for adata transmission sequence.

FIG. 3 is a block diagram illustrating an apparatus for interfacing awireless local area network and a wide area network or public switchedtelephone network in accordance with a first embodiment of theinvention.

FIG. 4 is a block diagram illustrating a wireless desk phone inaccordance with a second embodiment of the invention.

FIG. 5 is a block diagram of the protocol stacks that may be implementedin the wireless LAN in accordance with the invention.

FIG. 6 is a flow diagram illustrating a method for handling an outgoingcall in a wireless IP phone system according to the present invention.

FIG. 7 is a flow diagram illustrating a method for handling an incomingcall in a wireless IP phone system according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the figures, FIG. 1 shows a data communications networkin which the embodiments of the present invention may be implemented. Afirst local area network 100 is illustrated, including a host processor10 is connected by a wired communications link 11 to a number ofstationery access points or base stations 12,13; other base stations 14can be coupled to the host through the base stations or by an RF link.Each one of the base stations 12,13,14 is coupled by an RF link to anumber of remote mobile units 15 In one embodiment, the remote mobileunits 15 are hand-held, battery-operated data terminals portable digitalassistants or voice communication handsets such as described in U.S.Pat. No. 5,029,183; Ser. No. 08/794,782 filed Feb. 3, 1997, and Ser. No.09/008,710, filed Jan. 16, 1998, all assigned to Symbol Technologies,Inc., and incorporated herein by reference.

Various other types of remote terminals may be advantageously employedin a system having features of the invention; these remote terminalsordinarily would include data entry facilities such as a magnetic cardreader or the like, as well as a display (or printer) for indicating orproviding to a user information detected, transmitted and/or received bythe terminal. In this embodiment used as an illustrative example, theremay be from one up to sixty-four of the base stations (three stationsbeing shown in the Figure) and up to several hundred of the remoteunits; of course, the network may be expanded by merely changing thesize of address fields and the like in the digital system, as willappear, but a limiting factor is the RF traffic and attendant delays inwaiting for a quiet channel.

The first LAN 100 may be coupled to additional LANs 200,300,400 etc.through controllers such as bridges 50, 60, etc. or routers 55, 65, 75,85, 95, 105, etc. This communications network as seen in FIG. 1 wouldordinarily be used in a manufacturing facility, office building complex,warehouse, retail establishment, or like commercial facility orcombination of these facilities, where the data-gathering terminalswould be used for inventory control in stockroom or receiving/shippingfacilities, at checkout (point of sale) counters, for reading forms orinvoices of the like, for personnel security checking at gates or othercheckpoints, at time clocks, for manufacturing or process flow control,and many other such uses.

Although hand-held, laser scanning bar-code reader data terminals arementioned, the data terminals may also include bar-code readers of theCCD or wand type, and may be portable or stationery rather thanhand-held. The mobile units 15 may also be voice communication handsets,pagers, still image or video cameras; or any combination of theforegoing. Other types of data gathering devices may be utilized asterminals and use the features of the invention, such as temperature,pressure, or other environmental measuring devices, event counters,voice or sound activated devices, intrusion detectors, etc.

According to an important feature of one embodiment of the invention, anRF packet communications protocol is provided between the remote unitsand the base stations, and includes a transmit/receive exchange,referred to hereinafter simply as an “exchange”. This protocol issimilar to collision-sense multiple access (CSMA) in that a unit firstlistens before transmitting, and does not transmit if the channel is notfree. As seen in FIG. 2, this exchange always begins with aremote-to-base transmitted packet, representing an RF transmission froma remote unit to be received by the base stations within range. Thetransmitted packet is followed after a fixed time interval by abase-to-remote unit of RF information transmitted by the base stationservicing this particular remote unit. Each of these packets and is offixed timing; a transceiver in a remote unit begins an exchange at itsown initiative by first listening for other traffic for a brief intervalt_(o) (typically 0.3 msec.) and, if the RF channel is quiet, starting atransmission at a time of its own selection (asynchronous to any clockperiod of the base stations or host computer). This outgoingtransmission packet lasts for a time t₁ as seen in the Figure, and in anexample embodiment this period is 4.8 milliseconds. Then at a precisetime delay t₂ after it started transmission (e.g. 5 msec after thebeginning of t₁) the transceiver begins listening for the return packetfrom the base station. The transceiver in the remote unit only respondsto receipt of the packet beginning in a very rigid time window t₃ of afew microseconds length, and if the packet has not started during thiswindow then anything to follow is ignored. The packet is an acknowledgesignal, and also contains dam if the base station has any messagewaiting to be sent. The packet also is millisecond in length, regardlessof what data is included, if any, so a remote-to-base exchange,including acknowledge, takes about 9.8 msec in the example.

FIG. 3 is a diagram illustrating a first embodiment of the inventionshowing an apparatus 50 which combines the functions of a wirelesscommunication system access point and a telephony gateway in a singleunit in accordance with the present invention. In the discussion thatfollows, we will assume that the mobile unit 15 being utilized as avoice communication handset or wireless portable telephone, althoughother features such as keyboard data entry, magnetic card data entry,bar code reading data entry could be incorporated in such unit as well,and such unit utilized for simultaneous voice and data transfer over thewireless link. Since IP is the preferred network layer protocol, in thepresent invention, the handset may also be referred to as a “IP phone”in this patent specification, but it is to be understood that networklayer protocols other than IP could be used as well.

The apparatus 50 contains one or more transmitter/receivers 52 for radiocommunications to the mobile units. The transmitter/receiver 52 iscoupled to an access point Media Access Control (MAC) processor 54,which functions to send and receive data frames in the appropriateformat to and from the transmitter/receiver 52 at the appropriate times.The processor 54 is also coupled to a memory 58, which buffers datapackets.

Although in the present preferred embodiment the MAC processor 54utilizes an IEEE 802.11 data link protocol, other wireless LANs or WANsand other types of media access control, including FDMA, TDMA, CDMA, andcombinations thereof are also within the scope of the present invention.Different MAC processors may be used to accommodate two or moredifferent access techniques, including those of proposed MAC standardsof Home RF, Bluetooth, and others.

The memory 58 may be coupled to a switch or processor andmultiplexor/demultiplexor 60 which provides processing and switchingfunctions to route the data packets between the MAC processor 54 and anappropriate gateway. The switch or multiplexor/demultiplexor 60 may forexample be coupled to voice gateway 62, which utilizes signal processorand codecs to translate the voice packets into analog audio signalssuitable for transmission over a public switched telephone network orPBX. The switch or multiplexor/demultiplexor 60 may also be coupled toan analog modem gateway 64, which translates the digital datagrams fromthe LAN into encoded analog signals suitable for transmission over apublic switched telephone network, such as signals complying with theV.90 transmission protocol.

A Voice Gateway 62 also permits audio feedback from a telephone network(e.g. a busy signal) to an IP phone user in a wireless LAN system. Forexample, a series of feedback audible tones may be provided by thetelephone network, which are transmitted to the gateway, packetized, andtransmitted over the wireless link to the mobile IP phone. At the IPphone, the data packets are then converted into an analog signal,thereby producing an audible copy of the series of feedback audibletones.

In addition to the voice gateway interfacing to a wired telephonenetwork, interfaces to wireless voice and data networks may also beimplemented. There are also a wide variety of both analog and digitalcellular radio systems which are in use around the world for telephonyand data network applications. The digital ones include GSM, DCS 1800,IS 54 and others. To the extent there is available at the gateway alandline telecommunications system to the destination called party, theuse of a cellular radio system may be unnecessary and redundant.However, if such landline system is unavailable or has its serviceimpeded, the provision of a cellular radio system gateway is also withinthe scope of the present invention. Similarly, in certain remote areasit may also be desirable to provide a satellite radio system capability,such as connectivity to the Irdium phone network. Thus, themultiplexor/demultiplexor 60 may be coupled to any other appropriatetype of gateway 66, such as for xDSL, ISDN, FDDI, cellular radiotelephony (such as GSM), RAM, ARDIS, CDPD, or satellite radio networks.

The apparatus may also contain a cable modem interface for access to ahigh bandwidth cable network. A cable network is a network running ontraditional coaxial cable (which in most places, was originally designedto carry cable television signals). A cable modem MAC chip 68 is coupledto the multiplexor/demultiplexor 60 and controls the access to thephysical cable media (the actual transmissions travelling on the cablemodem network) and forms the cable network data frame. There are manydifferent cable modem standards and the apparatus may be designed to becompatible with any one of the standards. In the frequency-agilemultimode (FAMM) standard (a modulation technique of the IEEE 802.14standard), a preamble is inserted at the beginning of the data, with along preamble used for channel probing and equalization, and a shortpreamble used for fast resynchronization. Azzam, A. High-Speed CableModems. N.Y., McGraw-Hill, 1997. p. 213-19. Data in the body of eachframe is scrambled according to a pre-defined algorithm, and a cyclicredundancy check field is provided for error detection. The FAMMstandard supports several different modulation options, but all are atype of trellis-coded modulation (TCM).

If the apparatus is designed for use with the FAMM standard, atransmission over the cable would proceed as follows. The MAC chip 68would send the data to a scrambler and CRC generator 70, which scramblesthe data and generates the error-correcting cyclical redundancy checkfield. Then it is sent to a TCM encoder 72, which encodes the data intrellis-coded modulation form. A control signal is sent to a preamblegenerator 74, which then generates an appropriate preamble for the data.The preamble and data are both sent through a filter 76, which wouldmost likely be a digital pulse shaping filter, which is sampled at twicethe modulation rate. This information is then passed to an equalizer 78for equalization. The equalized information is sent through aninterpolator 80 (e.g. an interpolation filter), which interpolates theinformation so that the input to the digital to analog (D/A) converters82 is at a constant rate for different modulation options, After theD/As 82, the information is passed through lowpass filters and IQmodulation 84, for the final stages of the transmission process. Theinformation is then ready to be transmitted by a cable modem transmitter86, which sends the information over the cable utilizing control signalsreceived from a transmission-reception control circuit 88.

Signals received from the cable are received by a cable modem receiver90, which passes the information to a multiplexor/demultiplexor 92,which divides out the cable frequencies into channels. Each of thesechannels may carry independent information. Each channel of informationis sent through at least one digital signal processor 94, which performsthe appropriate receiver signal-processing functions and deliver thedecoded information conveyed in the body of a frame to the MAC chip.

Since the cable modem standards generally allow for very largebandwidths, the number of possible independent channels is very high.This allows for more users and devices to be used simultaneously. Forexample, if the apparatus supported eight independent channels, it wouldbe possible to have five independent mobile computer terminals accessingthe cable network while at the same time conducting three independentvoice conversations over the cable network.

Another feature of the present invention relates to providing rechargingand downloading cradles for use with the wireless handset, mobilecomputer terminals or portable bar code readers, (including pen-likereaders depicted in U.S. patent application Ser. No. 08/794,782). Theapparatus 50 may therefore optionally include a docking station or well96 which can be used to store and recharge the wireless handset ormobile computer terminal when not in use. It is also possible to designthe well 96 so that when the mobile unit 15 is placed in the well 96,the MAC processor downloads or retrieves data from the mobile computerterminal using an appropriate interface (electrical contact or IR) andeither stores it, or sends it out over the WAN.

The automatic downloading of data is useful in applications such as ashopping at home through an catalog of a company. The user may have asmall mobile computer terminal or portable digital assistant in whichthe user enters data of the items selected for purchase from thecatalog. When the user decides on a product to buy, he must communicatethat information from the mobile computer-terminal to the retailer. Inthe past, the next step would be to connect the mobile computer terminalto a host computer, either directly or through a wireless network. Thehost computer then utilizes a modem or similar interface forcommunicating with a home office of the catalog retailer. Using thepresent invention, however, as an alternative to implementing a wirelessLAN, the user may simply place the mobile computer terminal in the well96 when he has finished using it. Using power 56, the well 96 acts torecharge the mobile computer terminal, while also automaticallyaccessing information contained on the mobile computer terminal,including the retailer information and purchase information. Theapparatus then automatically routes the data to the appropriate gateway,dials the PSTN sales telephone number of the office of the affiliatedcompany or equivalently send out an IP network addressed message over anInternet connection and transfers the appropriate information. Theapparatus may access an electronically stored serial number of themobile computer terminal and transmit that to the company as well,allowing the company to look up a database entry for the user, the entrycontaining credit card, billing, and other important information. Thusthe user is able to complete an entire transaction by simply selecting aproduct by pen or keyboard entry on his mobile computer terminal andplacing the computer in a well 96. In a network including wireless IPphones, the well may be utilized to recharge the wireless IP phones in asimilar fashion to that of computer devices.

In addition to the gateway, in order for the access point to connectwith other access points on the network, the apparatus 50 may contain anEthernet, IEEE 802. X LAN, or similar data port 96. Serial interfacesincluding the Universal Serial Bus (USB) or IEEE 1394 bus could also beused. This allows a user to directly connect the gateway to other nodeson a wired LAN and transfer data in the form of 802. X packets or asserial data to and from the terminals, appliances or computers connectedto apparatus 50.

In addition, the apparatus 50 may include a communications controller 99having a plurality of communications ports, with a specific set ofaccess points in the network being connected by wire to a predeterminedport of the communications controller so that messages received by saidcontroller and destined for a particular mobile unit currentlyassociated with a specific access point are transferred to thecorresponding port of the communications controller and thereby to theassociated access point for communications to the specified mobile unit.

Another embodiment of the present invention includes a wireless desktelephone illustrated in the block diagram of FIG. 4. Such a wirelessdesk telephone is designed to communicate by radio to a stationary basestation of wireless LAN connected to a wired telephony network. Thetelephone 162 may appear like a normal desk phone, with a handset, cableand keypad, but rather than a phone line running to a RJ11 wall jack,the unit contains a battery and a transmitter/receiver 164 which allowsit to communicate using radio communications with one of the accesspoints on a wireless LAN, and to apparatus 50 or a gateway, and therebyto the PSTN or other telephony network. The design allows the desktelephone to be portable and moved into any area where it couldassociate with an access point without the difficulty or expense to runtraditional phone lines to the telephone.

The desk telephone includes a portable housing 162 including a keypad170; a handset 166 including a microphone and a speaker; and a cableconnecting said housing and said handset. A codec and signal processoris disposed in the housing for converting audio signals from themicrophone into digital signals or voice datagrams. A keypad processor172 is also provided in the housing for processing data (such as theextension or telephone number) entered on said keypad by the user into adestination network address to be used with the packetized digitalsignals. Circuitry first converts analog voice signals to digitalsamples using a coder-decoder (CODEC) using one of the ITU G.700 seriesstandards for voice encoding. A digital signal processing chip may thencompress the digital signal, since there is much silence and redundancyin most voice communications. Next, packets are formed from thecompressed signal stream A protocol stack software assembles a frameincluding the network address and the datagrams to be transferred over aradio communication link. A radio transceiver for communication framesincluding said packetized digital signals to and from a stationary basestation preferably using frequency hopping spread spectrumcommunications in the 2.4 GHz ISM band. These packets will normallycontain a header with a flag indicating that the packets contains voiceencoded data. This allows a network node such as a hub or router totreat a voice packet differently from packets containing data, since itis desirable in voice communications that there be very little delay inthe end-to-end transmission of voice packets, as opposed to datapackets, since packet data service will not greatly be compromised whenshort packet delays are introduced.

At the access point, the packet disassembly takes place. Packets areconverted to a serial data stream, uncompressed, and converted back toan analog voice signal. The appropriate gateway then transmits the voicesignal over the voice communication network. The entire analog to datato analog conversion is described in the H.323 standard.

At the other end, assuming there is another wireless network, thegateway converts the analog voice signals into digital data packets,which are then transmitted over the wireless network to the destinationIP phone.

The type of network software that may be implemented in a mobile unitaccording to the present invention is illustrated in FIG. 5. A varietyof different higher level protocols may be utilized in a Voice over IPsystem, as specified in the protocol stack of FIG. 5. In the preferredembodiment of the present invention, the PHY layer is a frequencyhopping spread spectrum (FHSS) radio frequency system. The link layer ispreferably an IEEE 802.11 MAC protocol. The network layer is preferablythe Internet Protocol (IP). Above the network layer, depending uponQuality of Service and other criteria, a number of different standardsillustrated in the Figure may be utilized.

The software for controlling the initialization of the various protocolstacks corresponding to different types of networks may include amultiple provider router (“MPR”) executing in the memory. For example,there may be two network drivers designated as driver A, and driver B.These network drivers are invoked by the MPR to authenticate an provideaccess to the specific network services provided by the drivers. Theinput/output devices may contain two distinct physical networkconnections and data buttering or storage devices associated with eachchannel.

The use of two network connections illustrate that the embodiments ofthe present invention may be operative in an environment where thecomputer system is connected to one or more networks and that thesenetworks may be heterogeneous. One skilled in the art will appreciatethat the methods of the present invention may be practiced on processingsystems with varying architectures, including multi-processorenvironments, and on systems with hard wired logic. Also, one skilled inthe art will realize that the present invention can be implemented in astand-alone environment where other types of drivers are used to supportsecure access to the communications services and channels that may beavailable.

Software systems often provide several application programminginterfaces (hereinafter referred to as “APIs”, or sets of routines) forcarrying out the methods of the present invention. Typical components ofthe software architecture include application programs, a multipleprovider router dynamic link library (“DLL”), and network drivers whichreside in the memory of the computer system. The MPR code implements aset of network APIs, which are network independent and can be used byapplications programs at higher levels on the protocol stack tocommunicate with the various network interfaces.

Special features can be implemented in the case where the wireless IPphone connects to a gateway to the PSTN. Most users are accustomed tofeatures which are common in analog landline telephones. These featuresinclude several signaling aspects including a dial tone produced when auser first picks up a telephone handset, a busy signal produced if adialed number is currently in use, a series of rings produced if adialed number has not answered, etc. The features may also includeredialing, speed dialing, conference calling, caller identification,etc. These features can be emulated in the apparatus when the LAN is awireless IP phone system and are typically performed in software.

FIG. 6 is a flow diagram depicting a method for handling an outgoingcall in a wireless IP phone system. At step 200, the system detects whenthe user activates the wireless IP phone, such as when the user hasentered the destination and activates a function key labeled “send”.This would be equivalent to what is generally known as “picking up” thetelephone. In portable telephones, however, the user does notnecessarily pick a telephone off of a base unit in order to activate theline, but may simply press a button labeled “call”, “on”, “talk”, orsomething similar. The wireless IP phone then sends a signal to theaccess point indicating that it has been activated for voicecommunications.

At step 202, the system sends an acknowledgement signal to the wirelessstation which produces a display signal indicating the station is on thenetwork. However, the advantage of waiting for acknowledgement from theapparatus is that there may be some “line checking” functions to beperformed so that the acknowledgement signal to the wireless IP phonewill not be sent if there is a problem with the wireless channel.Potential problems include the wireless IP phone being outside the rangeof the transmitter/receiver, excessive loading or network trafficprohibiting voice communications, or other difficulties that wouldresult in a quality of service below a predetermined threshold. If theIP phone cannot associate with an access point, or loses suchassociation, it displays “No Network” in the-display. In addition, whenthe phone is idle, and the wireless link is being impeded, the IP phonemay sound the out-of-range tone (one long beep and two short beeps).When the IP phone is active, and the connection is being impeded itsounds the call-waiting tone (two short beeps) to the user. The user hasten seconds to move within range of an access point on the networkbefore the IP phone automatically disconnects the call.

Once a “welcome” and positive status indication is produced, the usermay begin dialing a number. Therefore, at step 204, the system willdetect when numbers are dialed, and at step 206, the system will storethese numbers in memory.

At step 208, assuming a voice gateway connection, the gateway sends a“ring” message to the phone number being called. A “ring” messageindicates to the caller that it should produce a series of rings in theearpiece indicating that a caller is attempting to contact it. How this“ring” message is configured and signaled is largely dependent on thetype of wide area or switched telephone phone network to which theapparatus is connected. If the apparatus is connected to a cable modemnetwork, then the “ring” message would be encapsulated in a cable modemprotocol packet.

The cable modem protocol can briefly be described here. In the FAMMstandard, upstream frames begin with a preamble and end with a tailsequence. The preamble may be one of two sequences. The first is a longpreamble used for channel probing and equalization. This preamblesequence begins with a tone. After a period T, the phase of the tone isreversed. In the receiver, the phase reversal may be detected even whenthere is strong distortion that is encountered without equalization. Thephase reversal acts as a time marker, indicating the beginning of asubsequently transmitted sequence of equalizer training symbols. Thesecond possible sequence is a short preamble used for fastresynchronization. This is a short sequence of modulation symbols chosensuch that a receiver may establish the timing phase and carrier phasewith suitable processing methods.

The frame body contains protocol data and user data. This data isscrambled. It is then followed by a cyclic redundancy check (CRC) field,which is used for error correction. A tail section then follows iftrellis coded modulation (TCM) is used, so that it may reach a knowncode state before the end of the signal transmission. In the FAMMstandard; data rates between 0.5 Mbit/s and 16 Mbit/s are supported. Oneof ordinary skill in the art will realize, however, that there are othertypes of cable modem standards which may be utilized as well.

At step 210, the apparatus periodically sends a signal to the wirelessIP phone until the call is connected to produce a “ring” sound in theearpiece of the destination handset. The ring sound will most likelyemulate the commonly known “ring” sound of landline telephone systems(in timbre, length and time between rings). The ringing continues untilthe call is connected or until the user decides to decline the call bydepressing the “End” key.

Assuming the call is connected, the IP phone converts analog voice todigital packets using the steps described in connection with theembodiment of FIG. 4.

FIG. 7 is a flow diagram illustrating a method for handling an incomingcall in a wireless IP phone system. At step 250, an incoming “ring”message is received which includes a “phone number” of the caller'swireless IP phone. The usage of the term “phone number” herein includesnot only traditional PSTN phone numbers but any other means of uniquelyidentifying a user such as the IP address, or name through the use of acall management agent.

The called IP phone may then “ring” in accordance with whatever soundthe phone is designed to make when an incoming call is routed to it. Atstep 260, when the called user then activates the “send” key on wirelessIP phone to accept the call, the call will be connected. If the calleruser activates the “end” key, declining to accept the call, the call isdisconnected. Alternatively, the call may be connected to a voice mailserver to record a message from the caller.

In order to communicate a packet of data to a wireless communicationstation, the packet must include the address corresponding to anidentification network address of the wireless communication station. AnInternet protocol address (IP address) contained in the packet header isexemplary of an identification address which can be used to addresspackets of data which are to be routed over a network using TCP/IPprotocol to the communication station. The IP address is, of courseutilized when transmission are made pursuant the Internet Protocol.Analogous network addresses are used when data is to be transmittedpursuant to other protocols, such as the Novell IPX protocol, or theX.25 protocol.

Another feature of the apparatus according to the present invention isto supply a network address to a specific wireless handset thatcommunicates with it following authentication of the identity of theuser, and authorization only for the class of service assigned to thatuser. This feature is particularly useful in applications andenvironments in which the wireless handsets are initially not suppliedwith a fixed network address and not identified with a specific useruntil an authorization procedure is completed. Such applications areimportant in wireless network environments to control entry into anetwork and authorize association of wireless terminals or telephonyhandsets on the network. Since the communications protocols for wirelessnetworks are typically open standards, interoperable terminals orhandsets belonging to unauthorized users in range of a network accesspoint may be able to communicate with or listen to the network traffic,or utilize the network to communicate over private network facilitiesand channels. In the case of a network using the IP protocol, thenetwork address would be the IP address. For full generality, we use theterm “network address” in the discussion that follows, although in thepreferred embodiment that network address would be the IP address.

The proposed initialization and authorization procedure is as follows:the user picks up any handset among the several that may be availableand turns it on. A dialog box appears on the display on the handsetrequesting the user to provide a PIN number or password. The number isentered on the handset, and an network address is assigned to thehandset by a process to be described below. The apparatus then stores ina memory (for example, in a telephony gateway unit) the assigned networkaddress and associates it with the user's voice telephone networkidentity, such as referenced by the user's personal extension number ona corporate PABX system, or a telephone number in the PSTN. This storageprocess thus “registers” the current IP address of the handset in usewith the user identification. Such network address record is maintainedas long as the mobile handset is active.

The goal of the registration process is a convenience for authorizedusers that may have available more than one type of wireless handset, oreven several identical handsets, to select any one of them for use atany given time. In other words, the goal is to make any networkcompatible wireless handset available for use by any user, at any time,and at any place. Once the user identifies himself, on the handset and anetwork address assigned, the gateway and network is then able totransmit incoming messages to the user at the network address currentlyused by that specific handset. Since the extension number (or PSTNtelephone number) of the user is fixed, someone making a voice call tothat user (either by regular PSTN telephone or network Voice over IPtelephony) will typically use the fixed extension number of that user.The corporate PABX, or Voice over IP network, will route the call to thetelephony gateway server associated with that number, will then look upthe current network address of the specified user, and transmit themessages using the network address to the user over the Ethernet to theappropriate access point, or by RF broadcast from the correspondingaccess point.

The process of assigning an network address to a wireless handset may beperformed by a domain name server (DNS) or a dynamic host configurationprotocol (DHCP) server connected to the network. Such services providedomain name to network address translation and temporary assignment ofan network address to the mobile unit. Alternatively, the set ofavailable network addresses may be stored internally in a memory in thehandset itself, and a specific network address released to the user thatis associated with the user's identification.

Another feature of the present invention may be to automatically toprovide a set of parameter settings, or “class of service” options,associated with a particular user upon the wireless handset beingauthorized and registered. For example, a particular user may have alist of speed dial numbers, ringing options, of other personal optionsor features that the user would like implemented whenever a handset isactivated by that user. These parameters settings may be stored alongwith the PIN number or other authorization data. Once the handset isauthorized, the parameter settings are released from internal memory, orautomatically downloaded directly to the handset in use, and theoperational parameters of the handset are adjusted to such settings.

While embodiments and applications of this invention have been shown anddescribed, it would be apparent to those skilled in the art that manymore modifications than mentioned above are possible without departingfrom the inventive concepts herein. The invention, therefore, is not tobe restricted except in the spirit of the appended claims.

1. A method for handling an outgoing call in a network from a mobilehandset in a wireless communications local area network, comprising thesteps of: detecting, by an access point, when a user activates themobile handset to make an outgoing call; determining if a wirelesscommunication channel is available in response to the detection;transmitting an acknowledgement signal to the mobile hand set when thewireless channel is available; receiving a destination for the outgoingcall after transmittal of the acknowledgement signal; transmitting aring signal to a base station corresponding to said destination, saidring signal designed to alert a recipient that a call is attempting toconnect; and periodically transmitting a signal to the mobile handsetindicating that the call is being attempted until the call is connectedwith the recipient.
 2. A method as defined in claim 1, wherein thereceiving step comprise the step of receiving in the mobile handset anindication from the user of a type of call the user desires to make. 3.A method as defined in claim 1 further comprising the step ofdetermining in the mobile handset whether the user is making a networkaddress call, an intercom call, or a name call.
 4. A method as definedin claim 1 further comprising the step of receiving in the mobilehandset an audio signal and converting such signal into a sequence of IPdata packets and transmitting said IP data packets by radiocommunications to the base station.
 5. A method as defined in claim 4,wherein such radio communications is in the 2.4 GHz ISM band usingspread spectrum radio communications.
 6. A method as defined in claim 1further comprising the step of opening an H323 session through the basestation between the mobile handset and the recipient.
 7. A method asdefined in claim 1 further comprising the step of opening a voicechannel via a H.323 gateway between an analog voice channel and themobile handset.
 8. A method as defined in claim 1 further comprising thestep of sending a message from the base station to the mobile handsetthat association with the base station has been made.
 9. A method asdefined in claim 1 further comprising the step of sending a message fromthe base station to the mobile handset that the call is declined by thebase station.
 10. A method as defined in claim 1 wherein thetransmitting the ring signal step is performed by wirelesscommunications to the base station, then by circuit switched wiredcommunications to a destination node, and then by wirelesscommunications to a destination wireless handset.
 11. A method asdefined in claim 1 further comprising the steps of receiving by therecipient a sequence of IP data packets, and converting such packetsinto an analog voice signal.
 12. A method as defined in claim 1 furthercomprising the steps of receiving in the destination handset a sequenceof IP data packets and converting such packets into text for storage anddisplay by the handset.
 13. A method as defined in claim 1, furthercomprising the step of producing a ringing sound in the earpiece of adestination wireless handset to indicate that a call is attempting to gothrough.
 14. A method as defined in claim 1 further comprising the stepof producing a call waiting indication in the destination wirelesshandset to indicate that a call is attempting to go through when thewireless handset is in use.